This invention relates to line isolation circuitry and modem architecture for communication lines. More particularly, this invention relates to circuitry used in connection with isolation systems for connecting to phone lines.
New generations of consumer appliances like set-top boxes, payphones, vending machines and other systems often require or prefer low-speed data modems. Such modems allow remote hosts to handle billing or other housekeeping functions, or permit xe2x80x9csmartxe2x80x9d vending machines to call for more supplies. Although typical microprocessor and digital-signal-processor (DSP)-based multimedia chips employed in set-top boxes and other systems are capable of implementing a low-speed modem, they would do so at an undesirable manufacturing complexity and expense.
Prior modem architectures typically included multiple integrated circuits for handling modem processing and communication line termination. In particular, one or more digital-signal-processor chips have been coupled to analog-front-end circuitry, which in turn has been connected to line termination circuitry across a transformer isolation barrier. Such modem architectures suffer from numerous disadvantages.
The present invention provides an improved modem architecture and associated method that integrate modem and line-isolation circuitry so as to achieve modem functionality and system-side isolation functionality on a single integrated circuit.
The combined modem and line isolation system also includes a line-side line-isolation integrated circuit which contains caller ID circuitry. The caller ID circuitry includes a caller ID analog to digital converter for processing caller ID data. The caller ID analog to digital converter may be powered by a power supply generated from power provided across a capacitive isolation barrier. The caller ID circuitry may be coupled to the ringer inputs of the line-side line-isolation integrated circuit. The ringer inputs may be capacitively coupled to the phone line.